The present invention relates to a fuel supply pump, which is particularly suitable for easily volatiling fuel.
A supply pump having features of this kind is known from the 13th edition of the book "Die Pumpen" published in 1977 by Springer-Verlag, at page 279. In this pump the vent hole in the sealing surface between beginning and end of the side channel is a circular bore. The outlet opening is relatively small and extends radially over about the inner half of the width of the side channel.
It has been shown in practice that the known supply pump does not meet the requirements when it is used to supply easily volatile fuel, for example, gasoline, which has a higher temperature. In this case so much gas develops in the fuel that the necessary supply quantity is not reached and it takes an excessive amount of time from the starting of the pump to the point of time when it supplies the maximum quantity.
It is an object of the invention to develop a fuel supply pump comprising the features of the known pumps in such a way that the supply quantity is increased at higher temperatures. The higher temperature the fuel can have in a motor vehicle tank would for example be a temperature on the order of 60 degrees Celsius.